1. Field of the Invention
The present invention relates to a device for fixing a rotatable shaft in its axial direction within a bearing housing. The shaft is journalled in its axial direction, in a roller or ball bearing (hereafter, for convenience, referred to as a "roller bearing"), which is fixed to the shaft and bears against a fixed supporting surface in the housing with a force determined by a resilient element within the housing, the roller bearing thus having a measure of radial movability within the housing.
2. Description of the Prior Art
A device of the above-described kind is disclosed in U.S. Pat. No. 4,227,755 and is primarily intended for fixing the rotor shafts in a rotary compressor. It was previously known to maintain the roller bearing pressed against the supporting surface by means of an annular element which was screwed to the outer ring of the roller bearing. However, such an element must be tightened to just the right amount within the outer ring, and in practice this has proved difficult to achieve. Thus, if the contact between the annular element and the roller bearing was made to be too tight, the radial movability of the bearing was reduced (or even prevented), whereby the roller bearing was forced to take up radial forces as well as axial forces, which had an adverse effect on the life of the bearing. On the other hand, if the annular element was not screwed up tightly enough against the outer ring, the outer ring of the bearing could rotate relative to the supporting surface and the annular element, which may result in wear occurring further loosening the engagement and risking further damage. By arranging a resilient element, for example in the form of a spacing sleeve and a spring, which maintains the roller bearing pressed against the supporting surface with a specified force, as was proposed in the abovementioned patent, the problem of proper fixing of the roller bearing within its housing appeared to be solved. However, it has proved to be difficult to adjust the compressive force of the resilient element, so that, on the one hand, the roller bearing has the desired radial movability, while, on the other hand, the roller bearing, in operation of the machine, is able to absorb a sufficient axial force.